Field of Invention
The present invention relates to mechanical equipment manufacturing filed, specifically refers to the a combined ring rolling method for spherical valve body.
Description of the Related Art
Spherical valve is one kind of typical valve parts, which has extensive application in energy industry such as petroleum, natural gas, electric power, etc., and is very important for the safety and reliability of energy equipments. Valve body is the key component of spherical valve, which has spherical exterior surface and circular through-hole, is a kind of complex ring part with spherical profile. Because of the extreme working condition and high-performance requirement of spherical valve, the valve body usually needs plastic working to ensure its mechanical property. At present, spherical valve body used to be formed by conventional forging method: the ring blank forging with press machine is firstly carried out, then the rimming and profile shaping of ring blank is performed using spherical die and mandrel. This technology normally needs repeated heating and forging, leads to the high energy consumption, low efficiency and high labor intensity, furthermore, the poor forming accuracy and surface quality will expend a great amount of machining time and materials, thus the production cost increases significantly. The ring rolling technology is also considered for spherical valve body forming, however, as the ring has the features of profile cross-section and small rolling ratio, it was found that the profile shaping and diameter expanding are nonsynchronous during the ring rolling process, which leads to the profile cannot be shaped completely when the ring diameter reaches to the required dimension. So, in ring rolling for spherical valve body, the performing of ring blank under press machine is needed to avoid this defect, which increases the workstage and operating complexity thus also causes the much consumption of energy and time.